Fumigant material and method of fumigation



-Aug.1 1,1931. j 'HWHOUGHTON 1,818,136

) FUMIGANT MATERIAL AND METHOD OF FUMIGATION Filed March 5, 1928 gwuentoz Patented Aug. 11, 1931 STATES HARRY W. HOUGHTON, OF GLEN ECHO, MARYLAND, ASSIGNOR TO SAFETY FUMIGANI COMPMY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS EUMIGANT MATERIAL AND METHOD OF FUMIGA'EE'ION Application filed Liar-ch 5,

This invention relates to fumigants of the type comprising a lethal gas and a lachrymatory gas, or a gas which is both lethal and lachrymatory, and aims to provide a convenient and safe means for transporting and using the same. The invention consists in an improved assemblage of ingredients for generating the gas at the place of use with safety and convenience, and for storage and transportation prior to use without danger from fumes or handling.

In utilizing a fumigant gas, such, for example, as the cyanogen haloid (preferably chloride) and hydrocyanic acid gas described in myPatent No. 1,521,537, dated December 30, 1924, for fumigant and process of fumigation, difiiculty has been experienced in generating the gas at the place of use, due to the dangerous nature of the materials and violent character of the reaction if not properly controlled; and it has been found impracticable to generate the gas at a distance and transport it to the place of use in containers, such as pressure cylinders, because of the propensity of the gas to polymerization and decomposition into cyan uric haloid, which is not a fumigant.

I have found that the difficulties and dangers attending the generation of the gas at the place of use may be lessened by mixing the sodium cyanide and sodium chlorate, or other cyanide, haloid or oxidizing agent used, with a suitable binder and forming the mixture into a briquette which may be trans ported and stored with ease and safety. Sodium bromide or iodine or other advantageous substances may thus be added in desired proportions to the mixture without in creasing the difficulties of use. The reaction in the production of hydrocyanic acid, cyanogen chloride and cyanogen bromide from sodium cyanide, sodium bromide, 'and sodium chlorate and hydrochloric acid may be expressed by the following equation:

and probably in part by the following:

3NaCn NaClO NaC1+ NaBr 6HC1= 2CnC1 CnBr BNaCl 3330 1928. Serial H0. 259,321

The amount of cyanogen chloride is greatly in excess of the cyanogen bromide, and even more greatly in excess of the hydrocyanic acid. The equations when sodium iodide is substituted for sodium bromide are as follows:

amen Basic, NaI 7FIC1= 6NaCl HCn 2CnC1+ CnI SE20 3NaCn ivacio3 NaCl NaI enci 2CnC1+ CnI 6NaC1 enzo The amount of hydrocyanic acid gas produced varies with the proportions of the ingredients, the temperature and other condi tions, and the speed of the reaction, being greater the more violent the reaction. The gaseous mixture as normally produced is found to be a good germicide as well as an in= secticide and vermin exterminator.

The binding material or matrix forming the inert portion of the briquette is preferably a self hardening plastic easily decomposed by hydrochloric acid. Anhydrous sodium carbonate or other solid material having a low fusing point, or a mixture of cementitious substance, such as flour paste or sawdust or plaster of Paris, or lime or gypsum cement mixed with sand and water, and chemically inert in the sense that it is free from chemicals or impurities tending to react with the cyanide or oxidizing agent to set free hydrocyanic acid gas, may beused with successful results.

It is advantageous to protect the briquette from air and moisture by coating it with paraifine or wax paper that can be readily removed prior to use, or by covering it with a metallic foil or a container that will be dissolved by dilute hydrochloric acid.

During the summer months, particularly in warm climates, the acid, water and chemical ingredients may be so active as to-cause too rapid generation of the gases constituting the fumigant mixture, resulting in foaming and danger of injury to nearby articles due to the spllling of acid.

Under such special temperature conditions the parafine or wax paper wrapper may be left upon the briquette and holes or slits scraped or cut through it at one or more points so as to restrict the area over which the acid can attack the briquette and thereby delay and control the generation of the gas.

In the drawings, which are suggestive only, a

Fig. 1 illustrates a briquette of convenient shape, wrapped in parafline paper ready to be enclosed in a suitable container for shipment; and

Fig. 2 shows the briquette in a modified form of .parafline paper wrapping and enclosed in a cardboard box.

Referring to the drawings, the briquette (shown in Fig. 1) may be wrapped in damp proof paper 11 or other suitable material, and preferably is enclosed in a cardboard box or carton 12 (shown in Fig. 2) to protect it from injury. The briquette may be made ready for use by removing it from the box and stripping oil the wrapper, or if it is desired to delay the generation of the gas, instead of stripping the wrapper completely from the briquette, one side onl may be uncovered. The tear string 13 Fig. 1) provides a ready means for openin one side only of the briquette, or a series 0 holes 14 (Fig. 2 may be punched in the wrapper to permit access of the acid to the briquette without tearing or stripping the wrapper. The holes are covered b the wall of the box during shipment and andling, so that it is only necessary to lift the cover and tear off the front side of the box to expose them when it is de sired to use the briquette. A suitable matrix is prepared by mixing one part of lime with three parts of sand, slacking the mixture with water, and adding five parts of sand and enough water to make it semi-plastic. To this mixture-is added the chemicals, preferably in the proportions of eight parts of sodium cyanide and four parts of sodium chlorate, to which one or two parts of sodium bromide may be added if desired. No special preparation of these materials is required other than cracking the cyanide into small bits if procured in cake form. It is advantageous to add a few grams of common salt to accelerate the setting of the briquettes, which harden upon setting without application of pressure. Such a briquette does not deliquesce or give off fumes of hydrocyanic acid when exposed to air and moisture, and liberates the fumigant gas mixture freel whenreacteduponbyhydrochloricacid. A briquette or cake containing two ounces of sodium cyanide will require for its conversion into gas about nine ounces of hydrochloric acid and an equal volume of water, and will generate gas enough to fumigate five hundred cubic feet of space.

Such a cake, packed as above described, may be handled without danger, and when exposed to the mixture of acid and water it wi l react very slowly at first until the temperature of the water rises to over 100 F., which takes several minutes. This slowness in starting is advantageous, because it permits the user to get away to a safe distance after starting the operation.

Other advantages, such as the safety, ease and rapidity with which the gas can be generated at the place of use, and the cheapness of the materials used, commend the invention.

This application is in part a continuation of my application Ser. No. 143,526, filed October 22, 1926.

Without restricting myself to the particular ingredients and proportions mentioned, what I claim and desire to secure by Letters Patent is as follows:

1. A hardened cake of plastic material comprisinga cyanide, a bromide and an oxidizing agent in proportions to form cyanogen chloride in preponderant amount and cyanogen bromide and hydrocyanic acid gas in progressively decreasing amounts for the purpose described.

2. A fumigant produced by the simultaneous generation of hydrocya'nic acid gas in small amount cyanogen chloride in predominating amount, and cyanogen bromide in less amount by the action of a dilute hydrochloric acid upon a mixture of a cyanide in major amount, a bromide in minor amount and an oxidizing agent in proportion sufficient to prevent formation of hydrocyanic acid in considerable amount.

3. A fumigant having germicidal properties produced by the simultaneous generation of hydrocyanic acid gas, cyanogen chloride and cyanogen bromide or iodide by the action of dilute hydrochloric acid upon an inert mixture containing sodium cyanide, sodium bromide or iodide and a chlorate.

4. A caked mixture of a cyanide and an oxidizing agent with a protective binder in proportions to produce a stable lachryma-tory fumigant gas having germicidal properties by the addition of dilute hydrochloric acid, and packed in a wrapper having a portion adapted for partial removal, substantially as described. I

5. A eaked mixture containing sodium cyanide, a halide of an alkali metal, and a chlorate incorporated with a matrix of self hardening plastic material, and enclosed in a moisture proof wrapper with means for permitting partial access of an acid when used for the purpose described.

6. A hardened cake of plastic material comprising a cyanide, a bromide and an oxidizing agent in proportions to form hydrocyanic acid gas in minor amount and halogen cyanides in ma'or amount, and enclosed in a moisture fproo wrapper having removable portions or the purpose described.

7. An insecticide and germicide comprising a mixture of cyanogen chloride, cyanogen bromide and hydrocyanic acid gas in diminishing proportions, produced conjointly at the place of use, as and for the purpose described.

8. An insecticide and germicide comprising a mixture of cyano en halides in predominating amount an hydrocyanic acid gas in lesser amount, produced conjointly by the action of an acid and an oxidizing agent upon a cyanide and a halide inthe space to be fumi ated.

9. A umifant having germicidal proper- Q ties produce by the simultaneous generation of hydrocyanic acid gas, cyanogen chloride and another cyanogen halide by the action of dilute hydrochloric acid upon an inert mixture containing an alkali metal chlorate, an alkali metal cyanide and another alkah metal halide. v

In testimony whereof, I have signed my nametothiss ecification,

RY W. HOUGHTON. 

